Importance of the C12 Carbon Chain in the Biological Activity of Rhamnolipids Conferring Protection in Wheat against Zymoseptoria tritici

Rémi Platel (1) , Ludovic Chaveriat (2) , Sarah Le Guenic (2) , Rutger Pipeleers (3) , Maryline Magnin-Robert (4) , Béatrice Randoux (4) , Pauline Trapet (1) , Vincent Lequart (2) , Nicolas Joly (2) , Patrice Halama (1) , Patrick Martin (2) , Monica Höfte (3) , Philippe Reignault (4) , Ali Siah (1)

1 BioEcoAgro - UMR transfrontalière INRAE 1158
2 UTA - Unité Transformations et Agroressources [Université d'Artois]
3 UGENT - Universiteit Gent = Ghent University
4 UCEIV - Unité de Chimie Environnementale et Interactions sur le Vivant

The hemibiotrophic fungus Zymoseptoria tritici, responsible for Septoria tritici blotch, is currently the most devastating foliar disease on wheat crops worldwide. Here, we explored, for the first time, the ability of rhamnolipids (RLs) to control this pathogen, using a total of 19 RLs, including a natural RL mixture produced by Pseudomonas aeruginosa and 18 bioinspired RLs synthesized using green chemistry, as well as two related compounds (lauric acid and dodecanol). These compounds were assessed for in vitro antifungal effect, in planta defence elicitation (peroxidase and catalase enzyme activities), and protection efficacy on the wheat-Z. tritici pathosystem. Interestingly, a structure-activity relationship analysis revealed that synthetic RLs with a 12 carbon fatty acid tail were the most effective for all examined biological activities. This highlights the importance of the C12 chain in the bioactivity of RLs, likely by acting on the plasma membranes of both wheat and Z. tritici cells. The efficacy of the most active compound Rh-Est-C12 was 20-fold lower in planta than in vitro; an optimization of the formulation is thus required to increase its effectiveness. No Z. tritici strain-dependent activity was scored for Rh-Est-C12 that exhibited similar antifungal activity levels towards strains differing in their resistance patterns to demethylation inhibitor fungicides, including multi-drug resistance strains. This study reports new insights into the use of bio-inspired RLs to control Z. tritici.

Mots clés: wheat; Zymoseptoria tritici; rhamnolipids; elicitors; structure-activity relationship

Domaines: Phytopathologie et phytopharmacie

Rémi Platel, Ludovic Chaveriat, Sarah Le Guenic, Rutger Pipeleers, Maryline Magnin-Robert, et al.. Importance of the C12 Carbon Chain in the Biological Activity of Rhamnolipids Conferring Protection in Wheat against Zymoseptoria tritici. Molecules, 2021, 26 (1), pp.40. ⟨10.3390/molecules26010040⟩. ⟨hal-03183957⟩